The impact of psychosis on brain anatomy in bipolar disorder: A structural MRI study.

BACKGROUND: Bipolar disorder (BD) is a major psychiatric illness characterized by heterogeneous symptoms including psychotic features. Up until now, neuroimaging studies investigating cerebral morphology in patients with BD have underestimated the potential impact of psychosis on brain anatomy in BD patients. In this regard, psychotic and non-psychotic BD may represent biologically different subtypes of the disorder, being possibly associated with specific cerebral features. METHODS: In the present study, magnetic resonance imaging (MRI) at 3T was used to identify the neuroanatomical correlates of psychosis in an International sample of BD patients. A large sample of structural MRI data from healthy subjects (HC) and BD patients was collected across two research centers. Voxel based morphometry was used to compare gray matter (GM) volume among psychotic and non-psychotic BD patients and HC. RESULTS: We found specific structural alterations in the two patient groups, more extended in the psychotic sample. Psychotic patients showed GM volume deficits in left frontal cortex compared to HC, and in right temporo-parietal cortex compared to both HC and non-psychotic patients (p < 0.001, > 100 voxels). Psychotic patients also exhibited enhanced age-related GM volume deficits in a set of subcortical and cortical regions. LIMITATIONS: The integration of multiple datasets may have affected the results. CONCLUSIONS: Overall, our results confirm the importance of classifying BD based on psychosis. The knowledge of the neuronal bases of psychotic symptomatology in BD can provide a more comprehensive picture of the determinants of BD, in the light of the continuum characteristic of major psychoses.

Exploring the neuroanatomical bases of psychotic features in bipolar disorder.

Although bipolar disorder (BD) is traditionally conceptualised as one diagnostic entity, the heterogeneity of pathophysiological manifestations in BD suggests the need to classify the subtypes of the illness based on neural markers. Specifically, the presence of psychotic symptoms seems to be relevant for the clinical outcome and may have specific neuroanatomical bases. The main objective of the present review was to assess whether the distinction between psychotic BD (PBD) and non-psychotic BD (NPBD) can improve the identification of the neurobiological markers of this complex illness. To this end, we summarised the findings from the magnetic resonance imaging studies that explored the cerebral correlates of psychosis in BD in terms of grey matter volume (GMV). Overall, the results suggest the presence of peculiar GMV differences between PBD and NPBD. Specifically, psychosis in BD seems to be associated with cortical GMV deficits compared with both healthy controls and NPBD, mainly in the frontal region. Conversely, NPBD patients showed GMV deficits in selective regions of the basal ganglia when compared with the other groups. Taken together, this evidence confirms the importance to classify BD based on the psychotic dimension, which may have a specific neurobiological architecture that partially overlaps across multiple psychotic disorders.

Impairments of working memory in schizophrenia and bipolar disorder: the effect of history of psychotic symptoms and different aspects of cognitive task demands.

Comparisons of cognitive impairments between schizophrenia (SZ) and bipolar disorder (BPD) have produced mixed results. We applied different working memory (WM) measures (Digit Span Forward and Backward, Short-delay and Long-delay CPT-AX, N-back) to patients with SZ (n = 23), psychotic BPD (n = 19) and non-psychotic BPD (n = 24), as well as to healthy controls (HC) (n = 18) in order to compare the level of WM impairments across the groups. With respect to the less demanding WM measures (Digit Span Forward and Backward, Short-delay CPT-AX), there were no between group differences in cognitive performance; however, with respect to the more demanding WM measures (Long-delay CPT-AX, N-back), we observed that the groups with psychosis (SZ, psychotic BPD) did not differ from one another, but performed poorer than the group without a history of psychosis (non-psychotic BPD). A history of psychotic symptoms may influence cognitive performance with respect to WM delay and load effects as measured by Long-delay CPT-AX and N-back tests, respectively. We observed a positive correlation of WM performance with antipsychotic treatment and a negative correlation with depressive symptoms in BPD and with negative symptoms in SZ subgroup. Our study suggests that WM dysfunctions are more closely related to a history of psychosis than to the diagnostic categories of SZ and BPD described by psychiatric classification systems.